1. Field of the Invention
The present invention relates to double containment pipe systems. More particularly, the present invention relates to interlocking unions for double containment pipe systems. Still more particularly, our invention relates to double containment pipe systems having interlocking unions of synthetic resins reinforced with fiber glass.
2. Prior Art
A double containment pipe system is utilized for transporting fluids comprising an inner, or carrier, pipe, positioned concentrically within an outer, or containment, pipe. Both a carrier pipe and its related containment pipe are constructed by a series of pipe sections joined by pipe joints.
Traditionally, a carrier pipe system is intended to, and is constructed to, provide a means for transporting a fluid over a long distance efficiently and without allowing any of the fluid to escape from the carrier pipe system. The most common causes of escape of a fluid from a carrier pipe system are either a break in a pipe section, a break in a pipe joint, or a loosening of a pipe joint.
A carrier pipe system is constructed to be a safe and reliable means for transporting fluids, especially fluids which might be dangerous or which might contaminate the surrounding area should any escape from the carrier pipe system. Occasionally, a carrier pipe does fail and contaminating fluid covers the surrounding area.
The carrier pipe is normally independent from the double containment pipe which encloses it, and the double containment pipe is not in communication with the carrier pipe unless and until the carrier pipe should develop a leak. Then, the double containment pipe serves its basic purpose by collecting fluid escaping from the carrier pipe and becomes a means for transporting the fluid until the leak is discovered and repaired.
In any double containment pipe system the most elaborate component, and the component most likely to fail, is the pipe joint which joins two adjacent pipe sections of the carrier pipe system.
Pipe systems have been traditionally constructed of steel or other forms of metal. With the development of fiber glass reinforced resins, simple carrier pipe systems started to be constructed of fiber glass reinforced resins where such usage was permissible.
Double containment piping systems are, however, relatively new to the fiber glass resin pipe industry, and a great deal of the design requirements and capabilities of the fiber glass resin double containment systems are being developed even as the systems are being installed.